A number of medical devices, including elongated medical devices such as catheters and guidewires, are known. Such devices can include or be formed from a hypotube. In some cases, a number of slots can be formed in the hypotube to improve the flexibility of the hypotube. The resulting product is sometimes referred to as a micromachined hypotube.
A hypotube such as a micromachined hypotube may be subjected to one or more coating processes to provide the micromachined hypotube with a hydrophilic coating that lends biocompatibility and lubricity to the hypotube. As many hydrophilic coatings do not adequately adhere to many metals, a tie layer is oftentimes provided prior to forming the hydrophilic coating.
Unfortunately, a tie layer may negatively impact the flexibility of a micromachined hypotube by, for example, limiting relative movement between adjacent turnings or portions of the hypotube. Therefore, a need remains for improved tie layers that provide sufficient support for an overlaying hydrophilic coating. A need also remains for improved tie layers that do not negatively impact the flexibility of the micromachined hypotube.